ci(release): rustup target add before zigbuild (musl std missing in CI)

mise's rust.targets didn't install the musl std on the cached toolchain; add it
explicitly so cargo-zigbuild finds core for x86_64/aarch64-unknown-linux-musl.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: jaredLunde

.github/workflows/release-api.yml

@@ -21,6 +21,8 @@ jobs:
       - uses: actions/checkout@v7
       - uses: jdx/mise-action@v4
       - uses: Swatinem/rust-cache@v2
+      - name: Install rust target
+        run: rustup target add ${{ matrix.target }}
       - name: Build release binary
         run: cargo zigbuild --release --target ${{ matrix.target }} -p beyond-objects
       - name: Package